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Date: Mon, 14 Mar 2016 22:05:34 +0100
From: DK7FC <selberdenken@posteo.de>
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Subject: Re: LF: VLF preparations, today...
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Status: O

Hi VLF,

Today i've improved the reception of my VLF remote reception with the 
0.8m diameter loop.
http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber2.html
Quite low QRM levels i find.
I will try to get a trace of ZEVS, you remember? :-)
Still waiting for the GPS module. But maybe i will find the reason for 
the occasional phase glitches and can reduce them.

There could have been a faint trace of DJ8WX at 8270.00 Hz, which was 
not visible on the city grabber.

Ah, and, today it's the first time i was charging my smartphone onto the 
tree! 
https://dl.dropboxusercontent.com/u/19882028/MF/20160313_163417.jpg The 
Raspi needs 5V anyway and the DC/DC converter is strong enough. So i 
simply can switch it in parallel. I constructed a hanger to hold the 
phone while it is chared. So i can watch grabber windows out in the 
forest. And i can see my incoming spectrograms on VLF by using 
Teamviewer remote software. This allows me to align filter components 
and gain levels on the VLF preamp 
https://dl.dropboxusercontent.com/u/19882028/MF/20160309_152620.jpg :-)

73, Stefan

Am 13.03.2016 23:36, schrieb DK7FC:
>
> Am 11.03.2016 10:06, schrieb Domenico IZ7SLZ:
>> What about an VLF Ebnaut signal from you ?
>>
>> 73 Domenico, iz7slz
>
> In about 2 weeks i will prepare a small transmit (air cored) coil for 
> VLF. Markus/DF6NM has been here in Heidelberg a few days ago. He 
> kindly lent me his yoghurt-cup coil which has > 1 H. I measured 820 
> Ohm DC resistance but since my antenna C is about 470 pF, i can remove 
> some of the stacked cups.
> The advantage of the coming tests is that i will be able to transmit 
> under all WX conditions, even in rain and storm! I will also control 
> the phase of the radiated signal in a feed back loop to compensate 
> eventual phase changes (thermal variation of L; wire movement in the 
> wind...). So my signal could be very stable. It is already using 1pps 
> syncing...
> The disadvantage is that i am limited to about 200 mA antenna current. 
> So the signal will be even 10 dB weaker than in my last experiments 
> with the large coil. And it is about 30 dB weaker then the kite 
> experiments signal. An ERP below 100 uW.
> We will see if this makes any sense at all. I hope i can leave a 
> signal on my 3.5 km distant VLF remote grabber then ;-)
>
> Are YOU prepared to monitor traces in 47 uHz FFT BW ("DFCW-60000") ? 
> This will likely be the mode we can try. In EbNaut it will be most 
> difficult, maybe when using 100s symbols??
> Did you try to monitor the Alpha signals for some days, without seeing 
> phase glitches except one per day on 0' clock Moscow time?
> I'm still struggling to get my VLF remote grabber running on its best 
> performance using the 0.8m diameter loop. 
> http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber2.html
>
> 73, Stefan
>